Enhancement of the Higgs decay into a $Z^\prime$ pair in models with $U(1)_X$ gauge symmetry

Abstract

We discuss the Higgs phenomenology in models with a new $U(1)_X$ gauge symmetry including the $U(1)_{B-L}$ scenario, where three right-handed neutrinos are inevitably introduced due to the gauge anomaly cancellations. We find that the decay branching ratio of the discovered Higgs boson into a pair of new massive gauge bosons ($Z'$) can significantly be enhanced in the Dirac neutrino case as compared with the Majorana case for a fixed value of the new gauge coupling and the mass of $Z'$ under constraints from current experimental data. Because of such an enhancement, the Dirac case can indirectly be discriminated from the Majorana case via the Higgs decay.